dns_client_lib6.c

DNS 的实现代码

/*
 * DNS Resolver
 * IPv6 Resolver API
 *
 * Author: Pavel A. Bolokhov   <[e-mail]>
 *
 * @(#) dns_client_lib6.c,v 1.3 2005/12/19 13:45:25 sachinj Exp
 *
 * External API:
 *     dns_getipnodebyname()
 *     dns_getipnodebyaddr()
 *     dns_client_get_nameserver6()
 *     dns_client_flush_cachebyname6()
 *     dns_client_flush_cachebyaddr()
 *     dns_alloc_struct_hostent()
 *     dns_alloc_hostname()
 *     dns_alloc_aliases()
 *     dns_alloc_addrlist()
 *     dns_dns_hostent_to_hostent()
 */

#include "config.h"
#include "atypes.h"
#include "kernel.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include "dns_resolv.h"
#include "errno.h"
#include "messages.h"
#include "dns_resolv.h"
#include "dns_client.h"
#include "dns_client_util6.h"
#include "dns_client_resource.h"



/* dns_getipnodebyname --
 *     This routine constructs and sends either a DNS_GET_NODEBYNAME or
 *     DNS_GET_ADDRBYNAME message to the dns_client. If 'msg' is NULL
 *     then this is a blocking call, otherwise non-blocking.
 *     a blocking call for IPv4 addresses calls get_hostby() functions,
 *     whereas blocking call for IPv6 addresses calls the same
 *     function with 'msg' set to some non-nil value.
 *     a non-blocking call for IPv4 addresses invokes get_u_hostbyname(),
 *     whereas a non-blocking call for IPv6 addresses directly sends a
 *     message to dns_client.
 *
 *     Note, non-blocking call for IPv4 address resolution assumes 'hptr'
 *     field set in the 'msg' message.
 *
 * PARAMETERS
 *     hostname - domain name to resolve
 *     family   - protocol family (AF_INET or AF_INET6)
 *     p_err    - error values
 *     msg      - pointer to ATMOS_MESSAGE structure or NULL, see above
 *
 * RETURNS
 *     For blocking calls:
 *        On success, pointer to dynamically allocated hostent structure
 *        which must be released later by user via call of
 *        'dns_freehostent()'.
 *        On failure, returns NULL, and 'err' set to one of error values
 *        described below.
 *     For non-blocking calls:
 *        always NULL. on success 'err' is set to ESUCCESS, otherwise
 *        err is one of the described below error values.
 *
 * Error values:
 *     EINVAL          bad address family
 *     ENOMEM          not enough memory
 *     EHOSTNOTFOUND   specified host is unknown
 *     ENOADDRESS      name is valid but does not have an IP address
 *     ENORECOVERY     non-recoverable name server error occured
 *     ETRYAGAIN       temporary error occured - try again later
 *     ENONSADDRESS    no nameserver address provided, configuration error
 *     ENOSEARCHLIST   no search list provided
 *                     (when using relative hostname)
 */
struct hostent *
dns_getipnodebyname(IN const char *hostname, IN int family, IN int *p_err,
                    IN ATMOS_MESSAGE *p_msg)
{
    DNSC_DEBUG("entry\n");

    if (p_msg == NULL)  /* blocking call */
    {
        DNSC_DEBUG("blocking call\n");

        switch (family)
        {
            case AF_INET:
            {
                struct dns_hostent dns_hent;
                struct hostent    *p_hent;

                DNSC_DEBUG("AF_INET query\n");
                
                memset(&dns_hent, 0, sizeof(dns_hent));
                dns_hent.h_addr_list = calloc(MAXIPENTRYS, sizeof(U32));
                dns_hent.h_numaddrs = MAXIPENTRYS;
                
                *p_err = get_hostbyname(hostname, TRUE, &dns_hent);
                if (*p_err != ESUCCESS)
                {
                    DNSC_DEBUG("exit blocking - error %d\n", *p_err);
                    return NULL;
                }

                /* Convert 'dns_hostent' to 'hostent' */
                p_hent = dns_dns_hostent_to_hostent(&dns_hent);
                if (p_hent == NULL)
                {
                    *p_err = ENOMEM;
                    DNSC_DEBUG("conversation failed - no memory\n");
                }

                DNSC_DEBUG("exit blocking - error %d\n", *p_err);

                return p_hent;

            } /* case AF_INET */


            case AF_INET6:
            {
                struct hostent *p_hent;
                ATMOS_MESSAGE   local_msg;
                MSG_D_DNS_GET_NODEBYNAME(p_dns_msg, &local_msg);

                DNSC_DEBUG("AF_INET6 query\n");

                /* Non-blocking call must always return NULL */
                p_hent = dns_getipnodebyname(hostname, family, p_err,
                                             &local_msg);
                if (p_hent == NULL)
                {
                    if (*p_err == ESUCCESS)
                    {
                        awaitspecificmessage(&local_msg);
                        *p_err = p_dns_msg->error;
                        DNSC_DEBUG("exit blocking - error %d\n", *p_err);
                        return p_dns_msg->hent;
                    }
                    else
                    {
                        DNSC_DEBUG("exit blocking - failure %d\n", *p_err);
                        return NULL;
                    }
                }
                else
                {
                    ASSERT(FALSE);
                }

                break;

            } /* case AF_INET6 */


            default:
                break;

        } /* switch (family) */

    } /* blocking call */
    else
    {  /* non-blocking call */

        DNSC_DEBUG("non-blocking call\n");

        switch (family)
        {
            case AF_INET:
            {
                MSG_D_DNS_GET_ADDRBYNAME(p_dns_msg, p_msg);

                DNSC_DEBUG("AF_INET query\n");

                *p_err = get_u_hostbyname(hostname, TRUE,
                                          p_dns_msg->hptr, p_msg);

                DNSC_DEBUG("exit non-blocking - error %d\n", *p_err);

                return NULL;

            } /* case AF_INET */

            case AF_INET6:
            {
                ATMOS_MQID      qid;
                MSG_D_DNS_GET_NODEBYNAME(p_dns_msg, p_msg);

                DNSC_DEBUG("AF_INET6 query\n");

                if ((qid = findqueue(DNSCLIENT_QUEUE_NAME)) == 0)
                {
                    DNSC_TRACE("could not acquire the %s queue "
                               "handle\n", DNSCLIENT_QUEUE_NAME);
                    *p_err = ESRCH;
                    DNSC_DEBUG("exit non-blocking - ESRCH\n");
                    return NULL;
                }

                DNSC_DEBUG("Send message MSG_N_DNS_GET_NODEBYNAME\n");

                p_dns_msg->qcnt = 0;
                p_dns_msg->hostname = (char *)hostname;
                p_dns_msg->error = ESUCCESS;
                p_dns_msg->hent = NULL;
                
                *p_err = sendmessage(p_msg, MSG_N_DNS_GET_NODEBYNAME, qid);

                DNSC_DEBUG("exit non-blocking - error %d\n", *p_err);

                return NULL;

            } /* case AF_INET6 */

            default:
                break;

        } /* switch (family) */

    } /* non-blocking call */

    /* invalid family supplied */
    *p_err = EINVAL;

    DNSC_DEBUG("exit - EINVAL\n");

    return NULL;

} /* dns_getipnodebyname */


/* dns_getipnodebyaddr --
 *     This routine constructs and sends either a DNS_GET_HOSTBYADDR6 or
 *     message to the dns_client. If 'msg' is NULL then
 *     this is a blocking call, otherwise non-blocking.
 *
 * PARAMETERS
 *     addr  - address to resolve
 *     p_err - location of error value
 *     msg   - pointer to ATMOS_MESSAGE structure or NULL, see above
 *
 * RETURNS
 *     For blocking calls:
 *        On success, pointer to dynamically allocated hostent structure
 *        which must be released later by user via call of
 *        'dns_freehostent()'.
 *        On failure, returns NULL, and '*p_err' set to one of error
 *        values described below.
 *     For non-blocking calls:
 *        always NULL. on success '*p_err' is set to ESUCCESS, otherwise
 *        err is one of the described below error values.
 *
 * Error values:
 *     EINVAL          bad address family
 *     ENOMEM          not enough memory
 *     EHOSTNOTFOUND   specified host is unknown
 *     ENOADDRESS      name is valid but does not have an IP address
 *     ENORECOVERY     non-recoverable name server error occured
 *     ETRYAGAIN       temporary error occured - try again later
 *     ENONSADDRESS    no nameserver address provided, configuration error
 *     ENOSEARCHLIST   no search list provided
 *                     (when using relative hostname)
 */
struct hostent *
dns_getipnodebyaddr(IN const struct sockaddr *addr,
                    OUT int *p_err,
                    IN ATMOS_MESSAGE *p_msg)
{
    DNSC_DEBUG("entry\n");

    if (p_msg == NULL)  /* blocking call */
    {
        switch (addr->sa_family)
        {
            case AF_INET:
            {
                struct dns_hostent dns_hent;
                struct hostent    *p_hent;

                DNSC_DEBUG("AF_INET query\n");

                memset(&dns_hent, 0, sizeof(dns_hent));
                dns_hent.h_addr_list = calloc(MAXIPENTRYS, sizeof(U32));
                dns_hent.h_numaddrs = MAXIPENTRYS;

                *p_err = get_hostbyaddr(
                             ((struct sockaddr_in *)addr)->sin_addr.s_addr,
                             TRUE, &dns_hent);
                if (*p_err != ESUCCESS)
                {
                    DNSC_DEBUG("exit blocking - get_hostbyaddr failed\n");
                    return NULL;
                }

                /* Convert 'dns_hostent' to 'hostent' */
                p_hent = dns_dns_hostent_to_hostent(&dns_hent);
                if (p_hent == NULL)
                {
                    *p_err = ENOMEM;
                    DNSC_DEBUG("conversation failed - no memory\n");
                }

                DNSC_DEBUG("exit blocking  - error %d\n", *p_err);

                return p_hent;

            } /* case AF_INET */


            case AF_INET6:
            {
                struct hostent *p_hent;
                ATMOS_MESSAGE   local_msg;
                MSG_D_DNS_GET_HOSTBYADDR6(p_dns_msg, &local_msg);

                DNSC_DEBUG("AF_INET6 query\n");

                p_hent = dns_getipnodebyaddr(addr, p_err, &local_msg);
                if (p_hent == NULL)
                {
                    if (*p_err == ESUCCESS)
                    {
                        awaitspecificmessage(&local_msg);
                        *p_err = p_dns_msg->error;
                        DNSC_DEBUG("exit blocking - error %d\n", *p_err);
                        return p_dns_msg->hent;
                    }
                    else
                    {
                        DNSC_DEBUG("exit blocking - failure %d\n", *p_err);
                        return NULL;
                    }
                }
                else
                {
                    ASSERT(FALSE);
                }

                break;

            } /* case AF_INET6 */


            default:
                break;

        } /* switch (family) */

    } /* blocking call */
    else
    {  /* non-blocking call */

        switch (addr->sa_family)
        {
            case AF_INET:
            {
                MSG_D_DNS_GET_HOSTBYADDR(p_dns_msg, p_msg);

                DNSC_DEBUG("AF_INET query\n");

                *p_err = get_u_hostbyaddr(
                            ((struct sockaddr_in *)addr)->sin_addr.s_addr,
                            TRUE, p_dns_msg->hptr, p_msg);
                DNSC_DEBUG("exit non-blocking - error %d\n", *p_err);
                return NULL;

            } /* case AF_INET */


            case AF_INET6:
            {
                ATMOS_MQID      qid;
                MSG_D_DNS_GET_HOSTBYADDR6(p_dns_msg, p_msg);

                DNSC_DEBUG("AF_INET6 query\n");

                if ((qid = findqueue(DNSCLIENT_QUEUE_NAME)) == 0)
                {
                    DNSC_TRACE("could not acquire the %s queue handle\n",
                               DNSCLIENT_QUEUE_NAME);
                    *p_err = ESRCH;
                    DNSC_DEBUG("exit non-blocking - ESRCH\n");
                    return NULL;
                }

                DNSC_DEBUG("Send message MSG_N_DNS_GET_HOSTBYADDR6\n");

                p_dns_msg->qcnt = 0;
                p_dns_msg->addr = &((struct sockaddr_in6 *)addr)->sin6_addr;
                p_dns_msg->error = ESUCCESS;
                p_dns_msg->hent = NULL;

                *p_err = sendmessage(p_msg, MSG_N_DNS_GET_HOSTBYADDR6, qid);

                DNSC_DEBUG("exit non-blocking - error %d\n", *p_err);

                return NULL;

            }  /* case AF_INET6 */


            default:
                break;